Preparation of 1,3,2,4-Dithiadiazolyls

Certain dithiadiazolylium salts containing soft anions (particularly NCS and I ) show a tendency to decompose on heating or on dissolution to give the corresponding dithiadiazolyls [80JCS(D)1812 83JCS(P1)1181], 

The first dithiadiazolyl radicals were prepared by reduction of dithiadiazolylium chloride salts using sodium dust, triphenylverdazyl 43, or tetramethyl-p-phenylene diamine (82TL761). 

The preparation of 1,2,3,5-dithiadiazolyl radicals by rearrangement of the isomeric 1,3,2,4-dithiadiazolyl radicals in solution [86CC140 87CC69 92JCS(D)1277] will be described more fully in Section XXI.A.l. In the case of some multi-l,2,3,5-dithiadiazolyl radicals, this reaction occurs in the solid state on thermolysis (Section XXIII.G.3). However, this route is not a common preparative technique, since these radicals are more conveniently prepared by direct reduction of 2+ salts, as described in Section VII.B. 

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